City lifeguards in Haleiwa witnessed a large shark aggressively chasing fish close to the water’s edge Thursday morning.

Warning signs were posted at Haleiwa Alii Beach Park after the shark was spotted feeding on fish near the shoreline.

Lifeguards spotted the 13- to 15-foot shark at about 11 a.m. Thursday, according to Emergency Services Department personnel. Lifeguards issued verbal warnings and posted signs, and the beach remained open.

“It is not unusual for sharks to chase their prey,” the Aquatics Resources Division of the Department of Land and Natural Resources said in a written statement. “If something attracts a shark’s interest as a possible food source, it is normal behavior.

“What is unusual in this instance is that this was seen so close to shore.”

Annual seabird tracking begins on Garden Isle

The state will begin its annual three-month seabird monitoring on Kauai to help determine what is happening to Newell’s shearwaters and endangered Hawaiian petrels.

A radar truck of the Kauai Endangered Seabird Recovery Project will be out surveying the birds at 18 sites around Kauai until September, the state Department of Land and NaturalResources said in a news release Thursday.

The annual seabird radar monitoring coincides with the start of egg laying for both the shearwaters, which fall into a threatened classification by the federal government, and the petrelson Kauai.

Andre Raine, KESRP coordinator, said, “These sites have been surveyed since 1993 and provide us with over 20 years of data, which we can then use to see how the birds have beenfaring over the years. Unfortunately, so far the data has shown a huge decline since the early 1990s.”

The two species of seabirds fly back to their colonies only at night, making it extremely hard for researchers to see and count them, DLNR said. Radar overcomes this problem byallowing the radar operator to “see” the birds flying overhead in the darkness as a series of dots passing across the radar screen.

The radar truck will operate for the first two hours after dark to track the birds as they fly inland to their breeding colonies in the mountains, DLNR said. Radar will also be used for twohours before dawn, tracking the seabirds when they return to the sea.